I’ve been away on a “road trip” during the first part of June, so this month’s initial update is a trifle tardy.

After a 100k “break” yesterday JAXA/ViSHOP extent is currently in a tie with 2024 for 4th lowest for the date, and still slightly below 2012.

The PIOMAS sea ice thickness map for May 31st continues to show plenty of thick ice in the Beaufort and Chukchi Seas:

However, the associated volume graph shows the 2025 curve only slightly above the previous low for the date in 2017:

I have recently received a disturbing email from the NSIDC, which reads as follows:

Recent delivery from the US Navy of the SSMIS passive microwave data that the CDR sea ice product uses has become more sporadic. The Defense Department has informed NSIDC that they will reduce the priority of processing SSMIS data, resulting in likely daily data gaps.

Due to aging SSMIS sensors, NSIDC has already begun exploring alternative sensors, which led to incorporating the JAXA Advanced Microwave Scanning Radiometer 2 (AMSR2) prototype sea ice concentration in our latest version. Users may wish to begin utilizing those AMSR2 data as the SSMIS portion continues to degrade. As documented in NSIDC Special Report #27, the SSMIS-using CDR and its AMSR2 corollary are not yet fully intercalibrated. Users will see differences between the products, as AMSR2’s higher resolution provides better ice edge detection than SSMIS. We are developing a new version that will intercalibrate these sensors, though this will take time. We apologize for any inconvenience and appreciate your patience during this transition.

I clicked the link to read the special report, only to discover that the entire NSIDC web site is out of action this evening. Hopefully it will be back in action soon.

[Update – June 13th]

I tried clicking the NSIDC’s link to Special Report 27 again today, and thankfully it is now working! It contains much more information than this, but here are the NSIDC’s comparisons between SSMIS and AMSR2 data for the months of March and September:

In other news, snow melt is well underway around SIMB3 buoy 2025B, currently located at 165.2 W, 74.0 N in the Chukchi Sea:

Much more surprising news is that bottom melt appears to have started on the ice floe supporting SIMB3 buoy 2024V

This buoy is located in the Central Arctic at 113.5 W, 85.4 N!

Watch this space!